Ultraviolet Depth Lithography and Galvanoforming for Micromachining

Abstract

For advanced surface micromachining 3D UV‐microforming delivers excellent results. This low‐cost technology, a combination of UV patterning of very thick photoresist layers and molding of the resulting patterns by galvanoplating, opens a wide range of applications. An advanced spin coating and drying process was developed, which allows the homogeneous deposition of photoresist layers up to more than 60 μm in a single step. Simply by exposure to standard UV aligners and following immersion development, thick photoresist layers up to 100 μm could be patterned. Repeated exposures and developments were successfully used for structuring resist layers of more than 100 μm thickness. High aspect ratios of more then 10 and steep edges of more than 88° were achieved. The resist patterns were molded by electroplating. The widely used gold and nickel were completed by copper, zinc, and magnetic alloys like NiFe. If combined with sacrificial layers, this new technique offers a wide field for smart processing from the micron to the millimeter range. 3D UV‐microforming allows the use of materials with interesting properties which could not be provided by standard processes. It opens a way for faster acceptance of microfabrication in practice.